Reinforced light-weight concrete slabs



March 27, 1962 K. H. HELMERSON ET AL 3,026,652

REINFORCED LIGHT-WEIGHT CONCRETE sLABs Filed Oovl5, 1955 2 Sheets-Sheet1 jaw/3.5M

March 27, 1962 K. H. HELMERSON ET AL 3,026,652

REINFORCED LIGHT-WEIGHT CONCRETE sLABs Filed om. 15, 1955 2 sheets-sheet2 United States Patent Ofi ice 3,026,652 Patented Mar. 27, 19623,026,652 RElNFGRCED LlGHT-WEiGHT CNCRETE SLABS Knut Helmer Helmersonand Bengt August Helmerson,

Slielleftehamn, Sweden, assignors, by mesne assignments, to CasiusCorporation Limited, Montreal, Quebec, Canada Filed (het. 1.5, 1953,Ser. No. 3S6,264 Claims priority, application Sweden Jan. 3, 1953 3Claims. (Cl. Sil-78) One of the great advantages of light-weightconcrete as -a building material resides in the possibility of sawingit. Thanks to Ithis property, slabs and blocks of lightweight concretemay be worked and divided up according to requirements by means ofordinary woodworking tools. In this way a considerable .simplificationcan be effected in the erection of buildings, While at the same time thebuilding work will be less time-consuming.

In certain cases, particularly where large parts of lightweightconcrete, such as Wall-slabs, are concerned, it is necessary toreinforce the light-weight concrete products, particularly with respectto the stresses to which they will be subjected during transport to thebuilding site. This reinforcement, which usually consists of a number ofseparated, parallel iron rods interconnected by means of distance orjoining members in such a way that a reinforcing mat or cage isproduced, naturally exercises an adverse effect on the divisibility ofthe light-weight concrete slab and also on the wor-liability of thelatter in other respects, since both the parallel iron rods and thedistance or joining members which are usually also construoted of ironrods, have to be worked with a hacksaw or the like in order to cut them.

Investigations have shown, however, that it is seldom necessary todivide up the light-Weight concrete slabs in more than one direction,and as a rule they only require to be divided in the longitudinaldirection on the building site when delivered in standard lengths by themanufacturer.

The present invention takes advantage of this fact and has for itsobject to provide a reinforced light-weight concrete slab in which thereinforcement is arranged in such a way that the division of the slab isrendered possible by sawing with an ordinary wood saw in a directionwhich is substantially parallel with the iron rods forming thereinforcement.

The invention is chiefly characterized therein that the distance orjoining members are constructed of a material possessing approximatelythe same workability as the light-weight concrete of the slab. Thesedistance or joining members which should have as small a cross-sectionas possible are preferably so arranged that they extend to at least oneof the side edges of the slab in order to serve as carrying orsupporting elements for the iron rods when casting the slab. As examplesof suitable materials for the said elements, wood, especially plywood,also cardboard, cords or the like may be mentioned. Obviously, othersuitable materials which have the desired workability when compared tothe concrete per se may be substituted such as properly chosen plastics,concretes, fibrous materials or combinations of the foregoing.

With the foregoing and other objects in view, the invention resides inthe novel arrangement and combination of parts and in the details ofconstruction and process of manufacture hereinafter described andclaimed, it being understood that changes in the precise embodiment ofthe invention herein described may be made within the scope of what isclaimed without departing from the spirit of the invention. It will befurther understood that our invention is susceptible of embodiment inmany and various forms, some of which are illustrated in theaccompanying drawing, and that the structural details or par-ticularsteps of the method herein set forth may be varied to suit particularpurposes and still remain within our inventive concept.

Some forms of construction for a reinforced lightweight concrete slabaccording to the invention are illustrated diagr-arnmatically in theaccompanying drawings where, in all cases, the light-weight concreteslabs are partly broken away to expose the reinforcement.

FIG. l of the drawing is a perspective view of one form of a slabprovided with a reinforcement according to the invention;

FIG. 2 is a perspective view` of another form of construction;

FIG. 3 is a perspective View of a third form of the invention; whileFIG. 4 shows a fourth form of construction, also in perspective.However, the invention is not limited to the forms of construction shownin the drawings, which are merely to be regarded as examples of theapplication of the inventive principle.

In all the figures, 1 is the light-weight concrete slab which -isreinforced by a number of parallel iron rods 2 running in thelongitudinal direction. The ends of these iron rods 2 are located atsome distance inside the respective end surfaces of the slab to enableone or both ends of the slab to be cut obliquely, or to permit a slightadjustment of the slabs length, if necessary.

In FIG. l, the iron rods 2 are held together by a number of lwooden bars3 provided with holes through which the iron rods 2 run. The wooden bars3 extend to one side edge of the slab in order to serve as carrying orsupporting elements for the iron rods when casting the slab, and toindicate the direction in which the slab may be cut. It is obvious thatwith this form of reinforcement, the light-weight concrete slab I can besawed without difiiculty in `a longitudinal direction in any desiredmanner, as indicated by the wood saw 4.

In the light-weight concrete slab according to FIG. 2, Ithe wooden bars`are replaced by cardboard tubes -5 which run at right angles to theiron rods 2 and extend out to both side edges of the slab to serve assupporting elements for the iron rods 3 when casting the slab. The ironrods 2 are here rigidly connected to the cardboard tubes 5 by means ofWires or cords 6, but it is obvious that the cardboard tubes may also beprovided with holes in a corresponding manner to the wooden bars 3 inFIG. l, through which the iron rods 2 may be inserted. The slab in FIG.2 may hence also be divided in any desired manner in a longitudinaldirection with the help of an ordinary wood saw, which is indicated bythe saw cut '7.

In the light-weight concrete slab according to FIG. 3, the iron rods 2are interconnected by means of cords 8 which run between the oppositeside edges of the slab and are knotted around the different iron rods 2.During the casting of the light-Weight concrete slab these cords weremaintained stretched and have thus assisted in localizing the iron rods2 in the slab and it is obvious that the cords 8 will not prevent thesawing of the light-lweight concrete slab with a wood-saw or any otherworking thereof, in the direction indicated by the arrows 9.

Finally, FIG. 4, shows a further favorable form of construction withdistance `and joining members 210 of wood. These `are preferablyconstructed in the form of plywood strips to which the reinforcing ironsare secured by means of staples 11.

Although the supporting dist-ance or joining members of the typesindicated here do not, of course, possess the same reinforcing capacityas the ordinary cross-wires in a reinforcing mat or cage, theynevertheless act to hold the slab together, and before everything else,they fulll the function of iixing the longitudinal reinforcing rods 2while the light-weight concrete slab is being cast. Obviously, when oneend of a joining member is exposed as clearly shown in FIGS. l-4, thedirection of severing is indicated since the respective directions ofthe spacing element and the reinforcing rods are thereby known.

What we claim is:

1. A rigid structural building slab consisting of a body of light weightconcrete and a reinforcement capable of being sawn with an ordinary woodsaw, said reinforcement consisting of spaced, parallel, rigid metal rodscompletely embedded Within the body and extending substantially thelength of said body, said rigid metal rods having a shorter length thanthe dimension of said body in the direction of said rods, and joiningmembers running crosswise `and at right angles to said metal rods andinterconnecting therewith, said joining members being made of a materialpossessing at least the same ease of cutting as the light weightconcrete of said body, whereby the slab may be sawn entirely through ina direction substantially parallel with said metal rods by means of anordinary wood saw without obstruction from reinforcing parts which arediicult to sever, and said joining members having at least Itheir oneend exposed on tbe surface of said light Weight concrete body.

2. A method of manufacturing a plurality of reinforced concrete slabswhich comprises: connecting a plurality of metal reinforcing rods insubstantially parallel relationship by means of a plurality of joiningelements con strueted of ya material which possesses approximately atleast the same workability as the light-weight concrete of said slabs,casting a mass of light-weight concrete about said interconnected rodsand joining elements, and then cutting said cast mass in a plane betweentwo of said rods and completely through said joining elements, saidcasting being done with at least one end of a joining element exposed toserve as a carrying or supporting element for the metal rods when theslab is being cast,

3. A method of manufacturing a reinforced concrete slab which comprises:connecting a plurality of metal reinforcing rods in substantiallyparallel relationship by means of a spacing element constructed of amaterial which possesses, approximately at least, the saine workabilityas the light-weight concrete of said slab, casting a mass oflight-weight concrete about said interconnected rods and spacingelement, and then cutting said cast mass in a plane between two of saidrods and completely through said .spacing element, said metalreinforcing rods being made of iron and said spacing element made ofmaterial able to be readily severed, said spacing element beingelongated and positioned with at least one end exposed to serve as asupport when the slab is being cast and `to show the direction ofsevering by indicating the respective directions of the spacing element`and the rein-` forcing rods.

References Cited in the tile of this patent UNITED STATES PATENTS Re.20,275 Davis Feb. 23, 1937 799,988 Kane Sept. 19, 1905 983,209 CondieJan. 31, 1911 1,428,623 Birdsey Sept. 12, 1922 1,504,645 Rice Aug. 12,1924 1,570,538 Thomas Jan. 19, 1926 1,585,430 Smith et al May 18, 19261,761,848 Sitzman et al. June 3, 1930 2,087,218 Davis July 13, 19372,145,113 Fulcher Ian. 24, 1939 FOREIGN PATENTS 23,169 Finland 1949153,597 Sweden 1949 947,875 France 1949 991,064 France 1951

